1. Field of the Invention
Methods and apparatuses consistent with the present invention generally relate to encoding and decoding a multi-view image, and more particularly, to encoding and decoding a multi-view image in order to perform inter-view prediction and temporal prediction that are required for encoding and decoding at high speed.
2. Description of the Related Art
In multi-view image encoding, images input from a plurality of cameras that provide a multi-view image are simultaneously encoded. The multi-view image is compression encoded using temporal correlation and inter-view spatial correlation.
FIG. 1 illustrates sequences of a multi-view image according to a related art.
FIG. 1, a horizontal axis is a time axis and a vertical axis is a view axis. In multi-view image encoding, an intra (I) picture is periodically generated for an image from a base view and temporal prediction, or inter-view prediction is performed based on generated I pictures, thereby predictive-encoding other pictures.
Temporal prediction is performed using temporal correlation between images from a same view, i.e., in a same row. Inter-view prediction is performed using spatial correlation between images at a same point of time, i.e., in a same column.
In FIG. 1, each row shows an image sequence from each view for a multi-view image over time, and each column shows an image sequence from views 0, 1, 2, through to 7, sequentially from top to bottom. The view 0 is a base view and an image sequence in the first row is from the base view. Pictures included in the image sequence from the base view are predictive-encoded using only temporal prediction without using inter-view prediction.
Each column shows multi-view images at same point of time. Pictures included in columns 110, 120 and 130, in which an image from the base view is an I picture, are referred to as anchor pictures. The anchor pictures are encoded using only inter-view prediction.
Pictures included in the remaining columns except for the columns 110, 120 and 130 including I pictures are referred to as non-anchor pictures. The non-anchor pictures are predictive-encoded using both temporal prediction and inter-view prediction.
Among sequences illustrated in FIG. 1, a picture 141 in the second row and the fifth column will be taken as an example. Each block included in the picture 141 is predicted using inter-view prediction and temporal prediction. Since a prediction method may differ from block to block, reference should be made to pictures 142 and 143 in odd-numbered rows located adjacent to the picture 141 as well as pictures 111 and 121 that temporally precede or follow the picture 141, in order to predict the picture 141.
Similarly, according to the related art, the non-anchor pictures have to be predictive-encoded using inter-view prediction and temporal prediction that require reference to four pictures, resulting in low speed multi-view image encoding.